An electronic system is group of electronic components that are designed to work harmoniously as a collective whole; and, are housed within a mechanical package. Examples of electronic systems include networking systems (e.g., large scale or small scale routers, switches, wireless base stations, etc.) as well as computing systems (e.g., mainframes, workstations, servers, personal computers, etc.). An exemplary electronic system 130 is shown in FIG. 1.
Electronic components are typically mounted on cards (or xe2x80x9cbladesxe2x80x9d) which are plugged into a motherboard or backplane (e.g., via a card connector that is affixed to the motherboard or backplane). For example, as seen in FIG. 1, cards 102a through 102i are plugged into the surface 101 of a backplane or motherboard. Note that the number, shape, size, and positioning of the cards 102a through 102i and the backplane/motherboard 101 as seen in FIG. 1 are exemplary and may vary from embodiment to embodiment.
Frequently, each of the cards 102a through 102i are designed to perform a specific function that is consistent with the architecture and use of the system 130. For example, if the system 130 of FIG. 1 corresponds to a networking system, most of the individual cards 102a through 102i correspond to a networking adapter card which provides for one or more networking line connections to be made to the system 130. For example, card 102a may provide connections for 8 different Ethernet lines; card 102b may provide connections for 8 different T3 lines; card 102c may provide for 8 Synchronous Optical NETwork (SONET) lines, etc. Note that that the individual network lines are not drawn in FIG. 1 for simplicity.
During normal operation of the system 103, networking traffic (e.g., data, voice, etc.) received on a first networking line by a first card may be routed over the backplane or motherboard for transmission on a second line by a second card. For example, continuing with the exemplary networking system just described above, networking traffic that is received (within an Ethernet format) on a first line offered by card 102a may be routed over the backplane or motherboard to card 102c from where it is transmitted (within a SONET format) on a second networking line (that is offered by card 102c).
The backplane/motherboard 101 typically manages and/or transports the communications that transpire between the various cards 102a through 102i. The networking function of the system (e.g., the management and handling as to which networking line(s) the received traffic is retransmitted from) is typically distributed amongst the various cards 102a through 102i, or handled within one or more cards dedicated to this function (e.g., a routing card that corresponds to card 102e), or designed upon the motherboard/backplane 101, or designed with some combination of these techniques.
With respect to computing systems, the motherboard/backplane 101 typically house one or more processor semiconductor chips that execute the system""s software (although it is possible that computing machines may be constructed with processors distributed onto the cards 102a through 102i themselves) as well as manages or transports the communications that transpire between the various cards 102a through 102i. With respect to computing systems, cards 102a through 102i typically correspond to some combination of networking adapter cards (as discussed above), disk drives, memory expansions cards, video processing cards, etc.
Regardless if the system 130 is a networking, computing or other type of electronic system, however, the cards 102a through 102i and the motherboard or backplane 101 typically include electronic components such as integrated circuit (IC) semiconductor chips, discrete active devices (such as transistors) and discrete passive devices (such as capacitors, inductors, relays, transformers, etc.) that are cooperatively related according to an electronic circuit design. The electronic components on the cards 102a through 102i and the motherboard/backplane 101 are commonly surrounded by (and mounted to at various locations) a mechanical package 100 such as a metallic box-like or frame-like structure.
The electronic components, by the nature of their operation, are responsible for the consumption of electrical energy by the cards 102a through 102i and/or motherboard/backplane 101. The consumption of electronic energy results in the dissipation of heat. Electronic components are typically specified according to the temperature range of their surrounding environment (i.e. their xe2x80x9cambientxe2x80x9d). That is, minimum and maximum ambient temperatures are defined between which the electronic components are expected to maintain proper operation.
As proper operation of a system depends upon maintaining the ambient temperature of its electronic components within their specified ranges, the thermal environment within the mechanical package 100 becomes an important part of a system""s design.